Phytogenic crude phosphatides (e.g., derived from soybeans, peanuts, sunflowers or rape) comprise mixtures of about 30-40 percent of neutral oil and free fatty acids, about 5-10 percent of mono-, di-, or polysaccharides, about 50-60 percent of phosphatides and about 1-2 percent of sterols, waxes, amino acids and peptides. The phosphatide part usually consists of a mixture of phosphatidyl cholines, phosphatidyl ethanolamines, phosphatldyl inosites, phosphatidyl serines, phosphatide acids, N-acylcephalin and lysophosphatides.
Phosphatides are employed in large volumes in the food, cosmetic and pharmmaceutical industries. As a rule, a highly purified, oil-free phosphatidyl choline is required for use in the pharmaceutical industry. In order to obtain this degree of purity, it is imperative to remove the oil from the crude phosphatide. By this removal of oil, undesirable odorants and colorants are removed at the same time. The high purified, oil-free phosphatidyl choline is generally extracted from phytogenic phosphatides by means of a three-step proccss.
The first step comprises the acetonic removal of oil from the crude phosphatide to produce a product comprised of about 28-32 percent phosphatidyl choline and a maximum oil content of about 2.5 percent (See, for example, German Auslegeschrift No. 1 053 299; U.S. Pat. No. 3,268,335; German Auslegeschrift No. 1 047 597).
The second step comprises ethanolic extraction of the phosphatides to provide a product comprised of about 48-52 percent of phosphatidyl choline and a maximum oil content of about 2.5 percent. (See, for example, U.S. Pat. No. 2,945,869; U.S. Pat. No. 2,724,649).
In the third step the ethanolic extract phase of the second step is subject to treatment with aluminum oxide (usually by column-type chromatography) to produce a product comprising about 90-95 percent of phosphatidyl choline and a maximum oil content of about 2.5 percent. (See, for example, German Auslegeschrift No. 1 053 299).
This three-step process is very involved and expensive. It is further disadvantageous in that the two first steps require two different solvents (acetone and ethanol). A further drawback of the acetonic oil removal is the formation of acetone by-products such as mesityl oxide, diacetone alcohol, phorone, etc. which may only be present in small quantities but are undesirable because of their toxicity and their distinctive odor.
The method of the present invention overcomes the problem (previously unsolved by the prior art) of providing a simple, preferably single-step, inexpensive process for the production of an "oil-free" (i.e., oil content at most 2.5 percent by weight) phosphatide mixture having a high phosphatidyl choline content (48-52 percent) at high yields of phosphatidyl choline. Such a product may then be converted with the smallest possible quantity of aluminum oxide to a highly purified phosphatidyl choline.
As is described in the German Auslegeschrift No. 1 492 952 and the publication by A. Liebing, Seife-Ole-Fette-Wasche, 1972, Vol. 98, No. 12, pages 359 to 362, the extraction of crude phosphatides can be carried out with 80-95 percent ethanol. Using 95 percent ethanol, an oil-containing phosphatide fraction is obtained. The residual oil would then have to be removed in a second step by acetonic oil extraction to obtain a substantially oil-free product.
The extraction of crude phosphatides with 80 percent ethanol leads to a phosphatide mixture having an oil content of about 1 percent and a phosphatidyl choline content of only 31 percent. The phosphatidyl choline yield amounts to only 19 percent as shown in the comparative Example 3 hereinafter.
In U.S. Pat. No. 3,869,482, the production of phosphatides from animal organs is described. The production of phosphatides from animal organs presents problems of a different nature than does the production of phytogenic phosphatides. The problematic nature presented by the removal of the high oil content is only met in treating phytogenic phosphatides. Furthermore, the disclosed method involves a three-step process in which, in the individual purifying steps, alcohol as well as chloroform or benzene and petroleum ether are required.
U.S. Pat. No. 4,221,731 describes a separation of the phosphatides with the aid of a ternary mixture of hexane or benzene, alcohol and water.
U.S. Pat. No. 4,235,793 describes the production of an oil-containing phosphatide. Through the extraction of crude phosphatides with 85-95 percent ethanol, an ethanol phase is obtained which contains phosphatidyl choline and oil. In this case, no separation of oil and oil-free phosphatides occurs.
U.S. Pat. No. 2,090,537 uses as a starting material a lecithin which contains at least 58 to 78 percent of water. As can be seen from the disclosure of this patent, a separation into three phases does indeed occur, but as is mentioned at column 2, lines 15-25, all three phases still contain oil. As demonstrated in comparative Example 6 hereinafter wherein the disclosed process was reproduced, a product with an oil content of 12 percent was obtained. Therefore, the reference in claim 4 of that patent to "substantially fat- and oil-free" can only mean a partial rather than substantially complete oil removal. The product has a phosphatidyl choline content of about 25 percent.
In U.S. Pat. No. 2,356,382, a crude phosphatide sludge is used as the starting material which in itself contains large amounts of water. The process carried out according to this patent does not provide an oil-free phosphatide fraction since all fractions that are obtained still contain about 10 percent of oil in addition to the phosphatides. Example 7 hereinafter demonstrates that a clear separation of oil and phosphatidyl choline is not possible by carrying out the process of this patent.
The object of the invention of U.S. Pat. No. 3,652,397 is the production of a lyso crude phosphatide sludge (raw phosphatide with 44 percent of water) and pancreatine. According to the patent, the fatty acids that are released by the lyso formation and in part the oil from the reactive mixture are removed by addition of isopropanol. (See Comparative Example 8 hereinafter).
German Pat. No. 261 212 and U.S. Pat. No. 1,001,247 describe a process for the precipitation of phosphatides and oil from ethanolic oil-containing crude phosphatide extracts by the addition of water.